Abstract

The [Cu 4OCl 6(IMIDH) 4] complex has been synthesized and its crystal structure and magnetic properties determined. The compound crystallizes as a dark green solid in the orthorhombic system, space group P2 12 12 1, with cell constants a = 11.469(2) Å, b = 13.933(2) Å, c = 16.778(3) Å and four formula units per cell. The complex has a tetrameric structure of four copper(II) ions connected to a central oxo group, in an approximately tetrahedral arrangement. Copper coordination is completed by three ? 2-chloride ions and an imidazole nitrogen atom, defining a trigonal bipyramidal environment around each copper ion. A new Heisenberg exchange scheme has been developed, considering the experimentally observed distortion of the Cu 4 tetrahedron. The magnetic susceptibilities measurements were interpreted by means of this model, in terms of three coupling constants, J = -7.65 cm -1, J S = 83.3 cm -1, and JL = -58.8 cm -1, which show a linear correlation with the observed Cu-O-Cu angles. © 1999 American Chemical Society.